1. Field of the Invention
The present invention relates to the field of communications. More particularly, the present invention relates to improving reliability when interconnecting layer two and layer three networks.
2. Background Information
FIG. 1 illustrates an example of today's networking environment. In today's networking environment, layer two access networks 12 are often employed to access layer three core networks 14. Thus, a customer 10 can access the layer three network 14 using layer two access mechanisms. This approach combines the flexibility of maintaining layer two access with the flexibility of supporting multiple virtual connections from a physical access port. These multiple virtual connections are available without full mesh virtual connections among all customer sites due to the layer three connectionless forwarding capabilities.
An example of such a topology is an IP (Internet protocol) enabled frame relay/ATM (asynchronous transfer mode) network. Failures within the layer two network 12 are handled by the layer two failure recovery schemes. Failures within the layer three network 14 are handled by the layer three failure recovery schemes. Failures on the UNI (user to network interface) connections 16 between the layer two network 12 and the layer three network 14, however, are not protected by these recovery schemes and thus become single points of failure.
As shown in FIG. 2, a multi service platform 20 is conventionally provided in the layer three network 14. The multi service platform 20 includes layer two switching capabilities 22 and layer three switching capabilities 24. In today's multi service platforms 20, the layer two portion 22 is independent from and isolated from the layer three portion 24. Typically, the layer three portion 24 of the multi service platform 20 terminates the UNI connection 16. Thus, when the UNI connection 16 (either the link or a port) fails, the layer two network 12 will not re-route a circuit to the multi service platform 20 in the layer three network 14 because the layer two network only extends to the UNI connection 16. Although FIG. 2 shows a core layer three network 14, another layer two network may be provided instead of the layer three network 14.
Current solutions addressing the single point of failure problem include dual homing from a customer site 10 to the layer three core 14. In this case, when one connection fails, the other connection can maintain connectivity. This approach, however, consumes too many network resources by requiring both paths to be permanently maintained in the layer two network 12, also adding significant complexity to the provisioning and maintenance procedures for this service.
Another solution reduces the length of the UNI connection 16 between the layer two network 12 and the layer three network 14 by deploying layer two and layer three switches within the same central office. Thus, the connection 16 becomes an intra-central office connection. This solution, however, increases the overall switch deployment cost and is still subject to a single point of failure.
Thus, a solution is needed to address the single point of failure problem without increasing consumption of network resources.
Provisioning a circuit using current multi service platforms 20 entails a complicated two step process. Initially, the terminating multi service platform 20 is identified, and it is determined which layer two switch will connect to the multi service platform 20. A circuit can then be provisioned between the customer 10 and the identified layer two switch, which connects to the multi service platform 20. Finally, the layer three portion 24 of the platform 20 must be provisioned.
It would be desirable to have a simpler provisioning process.